In agricultural working vehicles, such as tractors, the transmission arrangements must cover very different driving ranges due to the very wide range of use of the vehicle. This requires a correspondingly large spread between the slowest and the fastest transmission ratio stages of the transmission arrangements. “Slow” and “fast” in this context refer to the resulting travel speed of the vehicle. Transmission arrangements for agricultural working machines generally also have small geometric stage intervals between individual transmission stages, so that in combination with the large spread, a large number of gears is the result. In transmission arrangements for agricultural working machines, this large number of gear stages can be implemented with a reasonable effort by a group design.
One possible structure for a transmission arrangement for an agricultural working vehicle consists of a main manual transmission, a downstream group-shift transmission and a reversing transmission, also referred to as a reversing unit. Usually a main manual transmission with narrow stages is used, the gear stages of which are designed to be powershift-capable, and a group-shift transmission, the shifting groups of which are not powershift-capable, however. In such a transmission arrangement, a change of gears by the main manual transmission can be done by powershifting, i.e. without interruption of traction force, within a shifting group of the group-shift transmission. If it is necessary to change the shifting group of the group-shift transmission, however, this cannot be done without interrupting the traction force.
Such a transmission arrangement is presented by DE 10 2010 029597 A1, in which the main manual transmission is designed as a so-called parallel-shift transmission.